1. Field of the Invention
The present invention relates to a liquid crystal display, and more particularly, to a liquid crystal display and corresponding method using a backlight unit that provides white light having an adjusted blue spectrum.
2. Description of the Background Art
A liquid crystal display includes a liquid crystal layer having a dielectric anisotropy formed between upper and lower transparent insulating substrates. Further, an electric field is applied to the liquid crystal layer to change the alignment of molecules of a liquid crystal material such that the amount of light transmitted through the liquid crystal layer is adjusted, thereby displaying a desired image.
Because the liquid crystal display is small in size, is light in weight, and has low power consumption, various devices such as a computer and a mobile telephone use liquid crystal displays.
Further, the liquid crystal display includes a color filter substrate, a thin film transistor array substrate, and a liquid crystal panel having a liquid crystal layer formed between the two substrates. The liquid crystal display also includes a backlight unit for providing light to the liquid crystal panel. The liquid crystal display may also include an external casing for protecting the liquid crystal panel and the backlight unit.
Hereinafter, a liquid crystal display in the related art will be described in detail.
As shown in FIG. 1, the related art liquid crystal display includes three red (R), green (G) and blue (B) sub-pixels forming a unit pixel Pa to provide a dot. Further, a plurality of dots is displayed on a frame to display a desired image.
As shown in FIG. 2, the unit pixel Pa includes a color filter 23 having red (R), green (G), and blue (B) filters 23a, 23b and 23c. The color filter array substrate also includes a transparent substrate 21 and a black matrix 22 formed on the transparent substrate 21. The black matrix 22 is for defining sub-pixel regions and blocking light leakage. The color filter array substrate also includes an overcoat layer 24 for planarizing the color filter layer 23.
Further, the black matrix layer 22 is formed on the transparent substrate 21 in a matrix shape and blocks light transmitted through the thin film transistor array substrate. Also, the color filter layer 23 exhibits a desired color corresponding to a light signal transmitted through the thin film transistor array substrate. In addition, the overcoat layer 24 compensates a step difference of the color filter layer 23 and protects the color filter layer 23.
As shown in FIG. 3, the light generated from a light source 30 (e.g., fluorescent lamp) disposed on the rear surface of the liquid crystal display is transmitted through a thin film transistor array substrate 10 and the color filter layer 23 to emit red (R) light, green (G) light and blue (B) light. At this time, image information is displayed by mixing the red (R), green (G) and blue (B) light. An example of a displayed image is shown in FIG. 4.
As shown in FIG. 4, the displayed image has a relatively low definition and brightness. That is, the light emitted from the backlight unit is transmitted through a first polarizer (not shown), an optical sheet (not shown), the thin film transistor array substrate 10, the liquid crystal layer, the color filter array substrate 20, and a second polarizer (not shown). Accordingly, the displayed image has a much lower definition and brightness, compared to the light emitted from the backlight unit.
Further, due to the structure of the related art liquid crystal display, it is difficult to improve a contrast ratio and brightness of the image.